Sequential starting of independent free piston engines



Aug. 5, 1952 R HUBER 2,605,605

SEQUENTIAL STARTING OF INDEPENDENT FREE PISTON ENGINES Filed June 6', 1949 2 J A J 1 5 1m 4 I v 7a Z2 1.? J6

' I 32 J? 15 Z5 7 35;? U 362 Z2 IN VE N TUR I Roan HuBER TTORNE Y Patented Aug, 5, 1952 latossos i I SEQUENTIAL STARTING, OF INDEPENDENT 7 .FBEE'PISTON ENGINES 'litob ert fluber,Bellevue, France, assiglior' to S ci'ete dEtudes -8z de Participations Eau, Gaz, Electricite; Energie, S. A., Geneva,-Switzerland,- a-society of Switzerland fiApplicationJunefi,1949, SerialNo.97,466 if In France June 16, 19 48 The present invention relates J to starting con trol devices forplant's-including at least two? free piston machines each of whichis provided with at least one starting cylinderinto which is introduced, at the time of starting, a-cert'ain amount of gas under --p'ressur'e', in particular of air under pressure, this introductiontaking place as a result of the opening 'of a valve which. is controlled through pneumatic means and which will be hereinafter called starting valves.

Its object is toprovide starting-control devices for plants of the kindin question which are better adapted to -meet the requirements of: practice than those used up to thistimerin particular which ensure in a particularly simple manner the starting of -at leasttwo-free piston machines: with a predetermined phase-(inference between My invention consists" chiefly in controlling the respective pneumatie'means for openin'g the starting valves of at. least two free. piston. machines. through a common operating. member. and in differentiating the-rates of: flowj and/or the masses of the' respective gasx streamstwhich are to be setrinmovement' inc'said penumatic' means for opening the corresponding. starting valves,;so-as to. produce, a lag between the opening of one. valve andthat of. the. other, this lag. when. the number .of free piston machines con-1 trolled by the same operating. member is, 2 equal to two, bein chosen;,.equalt0.about ;one; .half; of the period of reciprocation; or; oscillation vof the free pistons onto: an odd: multiple; ofzthis. value. v

" .j 'icam'... (01. 60-14) auto-generators includes-a motor' cylinder l,

working preferably'on the two-stroke cycle and on the dieselengine principle, which means that the fuel injected-by an injector ziis' ignited by the heat of compressi'on of the comburent agent compressed, during the inward stroke; by the motor piston 3 working in the motor cylinder l. Motor cylinder I is fitted withat least one inlet port 4 andone exhaust port'fi; both controlled by motor piston 3 This motor piston 3 i is rigidwith a compressor' piston 6, these two pistons -3 and 6 constituting a movable unit. Furthermore, motor cylinder I is made rigid with a compressor cylinderF-l fittedzwith aninlet valve 8 and a discharge valve 9 and in which cylinder said compressor piston 6 is running. Around motor cylinder i thereis provideda casing It which serves to:: receive. the air compressed by the innerfacejof. compressor piston 6 and which communicates with the inside of motor cylinder I when piston 3is'in: a position close toits outer Preferred embodiments,- of theJpresenti invem tion will be hereinafter describedwithreference to the accompanying-, drawing, given merelyby way pf. example and ;in which; n

. 1 d a rammatica ly s ows. a. plantin-.. cluding two free piston machines andfitted; With st r in 9 0 llii f c din v: 99. 1. e ri;

Fig. 2 shows 'anotherembodirnent of such a starting control device;

Fig. 3 shows another embodiment.

y invention In the following, description,

be supposedjt'o be applied .to the asser a plant including two free. pl

. s 9 'ai i r eh alo fo Pmfically me. wishe nd a r eiver machine, for'i'nstance. a turbine supplied with erators. I I V Concerning autorgenerators A and B they are made, with the exception of their' st arting control devices, of. any'suitablegconstruction, for instance as's'liovvl-nb'y Fig 1, where each of-these;

the motor'gase's. deliverediby these sum-gen:

dead center position and. clears inlet port 4.

In order to ensure-thelreturn stroke of the movable-unit 3--6:of' each of the auto-generators A and B-that isto say'thestroke during which the massofairiimprisoned inimotor cylinder I is compressed to reach atemperaturesufficient for producing ignition of the fuel. injected by means of injector ZSandLin the course of which the air-present in the inner: part of compressor cylinder]. is compressed and delivered into casing I0+I make. use of supplementary:aircushions' which, in the autoi-generators'sh'own by ,Fig. 1, are each imprisoned: betweenthe outer'face of a compressor piston 6. and theiend wall la of the corresponding compressor cylinder 1;. These cushions store'upmost of the energy developed inmotorcylinder l during the outward stroke of movable unit 3.:fi,:;to;restore this-energy to movable unit3 6 duringthe inward stroke.

. The -free -piston machines are started by. introducing, into each of thesp'aces provided for these air cushions, acertain amount-of air which expands. di l h :wrrespon i i Piston unit. 3 -6" toward its innendead center position, so as j thus to compress the air present in motor cylinder 1 and toig'nite the amount of fuel injectedat the end of this. inward stroke. a For this purpose, I 'prQvide, in the end" wall id of each of the compressor cylinders tan aperture II which is controlled by a valve I2, which constitutes the above mentionedstarting' valve.

the end wall 'mpr compressor cylinder 7' and fitted, all? .its'outer end, with" a"cy1inder M in conduit I! may extend through piston l5 itself.'

In order to start the machine, it suffices to fill up chamber l3 with air at a sufiiciently'high pressure and then quickly to open starting valve I2 so that the mass of air imprisoned in chamber I3 quickly enters the space between the outer face of compressor piston 6 and the end'wall 1a of the compressor cylinder.

For this purpose, I provide an air conduit-l9 opening into one end of cylinder I4. The air under pressure supplied through this conduit passes through conduit I1, Once chamber 13 is filled, conduit 19 is placed in communication ,with the atmosphere, sothat the air present on the outerside of piston 15 can escape to theflatmosphere'. Thepressure acting upon the inner face of piston'l5 can thus open starting valve l2, against. the action of spring l6 and the air present in chamber [3 on the inner side of piston l starts the free piston unit into operation. The starting valve I2'is thus controlled through pneumatic means.

In the case of a plant including at least one group of two auto-generators A and B, it is advantageous, on the one hand, to connect together, bymeans of a communication conduit20, the two casings II] of the two auto-generators A and B and, on the other hand to. connect with a common conduit 2| the exhaust; ports 5 0f the motor cylinders of these. two auto-generators, while managing so that the movableunits of the two auto-generators A and'B work with a phase difference equal to about one half of, theperiod of reciprocation of their movable units, which means that, when the movable unit of one of these generators is in its inner dead center position, the movable unit of the other generator is in its outer dead center position.

With such arrangement, it is possible to reduce thedimensions'of the casing [0 of each of these auto-generators and to steady the flow of the motor gases through conduit 2|: toward a receiver machine,.for instance a gas turbine 22.

In order to maintain this phasedifierence between auto-generators A and B during their operation, I may have recourse to. any suitable device 23, in particular toone of those described i my U. S. Patent No. 2,473,204.. 1

In order to obtain this phase diiference as soon as the plant is started, according to the main feature of my invention, the pneumatic control devices of the starting'valves l2 of auto-generators A and B are controlled by a common control member 24 and I provide means capable or differentiating either the rate of flower the mass,

or again both the rate of-flow and the mass of the gas streams which are made to escape to the atmosphere to operate pneumatic means l3-l4- I5 so that one of the starting valve opens with a certain lag with respect to theother, this lag being chosen equal to aboutone half' of the period of reciprocation of the free pistons or to an odd multiple of this value.

In order to differentiate the flow rates of the masses of air which, in cylinders l4, act upon the outer faces of pistons l5 and are made; to

escape to the atmosphere'through control mem-' ber 24 and conduit 2411, I may 'give'diiferent values either to the respective lengths of conduits [9 or to the cross sections of at least portions of these conduits, or again to both the lengths and the sections of these conduits. Thus, in the embodiment of Fig; l; the conduit l9 which connects control member 24 with the starting chamber I3 of auto-generator B is provided with a check valve 25 opening toward the cylinder l4 of this auto-generator and short-circuited by a by-passi conduit 26 of reduced cross section which slows down the flow of air from this cylinder whereas the conduit [9 corresponding to auto-generator A is free from any such slowing 'downme'ansl- It should further be noted that the same coninto chamber l3.f

trolmember 24. serves, in the plant illustrated by Fig. 1, tothe filling up of chambers I3 with starting air. In order to obtain this, it suffices to bring the handle 21 of member 24 into the position shown by Fig. 1, so as to connect the two chambers 13 of generators A and B with a compressed air tank 28, thejfiowof air being not interfered with by check valve 25, which opens in the direction from tank 28 toward the chamber l3 of generator B. In order to obtain starting, the handle 21 of control member 24 is broughtinto the position shown in dot-and-dash lines, whichbrings conconduits l9 into communication with the atmosphere. The outflow-of the air present. on the external faces of pistons l5'is1quicker for generator A than for generator 2B,;the, difference in rate of flow being chosen such that once control member has been .broughtinto the position shown by Fig. 1,- the valve 2;-of generator A opens before the valve l2 of generator'B; the lagbetween these openings being about equal to one half of the period of reciprocation of thefree pistons,'which is substantiallythe same for machines A and B. In this way, themere pivoting of member causes first generatorA-to start and them-after. a time interval equal to half a period; generator B, whereby the operations. of these two generators aregiven, from the start, the desired phase. difference between them.

Another embodiment'of my invention, according to whichithe desired phase difference is also obtained by'giving different rates of flow to the air streams the. outflow. .of'iwhich permits the opening lot the. startingzvalves, is shown by Fig. 2 which represents a starting device particularly advantageous in the 'ca'se 'o'f' two generators or other free piston machines disposed in .line with each other. In this figure, I have shown only the portions 'o'ffthese' twov auto-generators in the end walls 1d of which are provided starting valves 12 analogous to the starting-valves of the embodiment of Fig. 1. Whehlcontrol member 24 is in the position shown by Fig.2." starting air flows from reservoir'28; past check valves 2 9, into starting air chambers l3 and past check valves 3 lj into which causes valves I2 to; 1 takes 'place, ac

cording to Fig.2, underthe effect of the; opening of a valve}! kept in thef'closed position as long as control memberl24 is iii-the position. shown by Fig. 2, inwhich the pressure of the starting air acts upon'the external face of a piston 32 rigid with said valve 3|. If, on the contrary, control member 2 4 is rotated through .so that conduit 33,; through-which starting air wasfed'to the starting device, is now in communication with.

the atmosphere through conduit 34, valve 3| aeoacot opens under the influence of the pressure of the mp i ned 1 c lin e I41: and ,whie a through openings"35 a'-'and-35b'--on' the externaliacefoffpiston -32 -rigid with valve Asthe cross sectionofopening 35c is ramme-earner of opening 35b, the air presentin the cylinder I l which corresponds- :tof opening35aescapes at a higher rate pastvalve 31 than 'thei'airpresent chines A; and B communicate togeniemo iia ge the chamber E3 of the starting device climachine B, which starts after the other machine A, up to a slightly higher pressura'in order to make allowance for the overpressure that is produced during. the;first stroke of the first generator. I may obtainsuch. a diiference of pressure between the two chambers for instance by loading the two valves [1 and 291'by means of springs 29a. (Fig.2) exerting slightly different forces, the spring 290: of the starting device of the machine that is to start firstbeing Sl ghtly stronger and consequently producing afislightly higher difference of'pressure between conduit 33 and the'cliamber I 3 of this first starting machine than the spring 29c interposed between: the conduit 33 and the chamber 1310f the second I startmg machiner- V.

In both of the embodiments above described, the interval between the times ofstarting of the two free piston machines-is a consequence of the difference between the; rates of flow-with which air under pressure escapes from "cylinders l4. However, as already above stated, this phase difference might also be obtained by an arrangement of the pneumatic devices which control starting such that the masses of air which are to escape to cause the starting valves to open are different. This difference between the air masses may be obtained by a diiferent choice of the return forces of springs I6, this diiference having for its effect to start the free piston machine which has the stronger spring after the other free piston machine. An analogous effect might be obtained by filling the cylinder l4 of one of the two generators with a mass of air having a pressure higher than that of the air present in the cylinder M of the other generator.

In the embodiment illustrated by Fig. 3, one of the cylinders [4 (the one on the right hand side of the drawing) has its portion on the outer side of piston I5 greater than the other cylinder, so that the mass of air which is to flow out to open one of the starting valves is greater than that corresponding to the other valve.

In all cases, the antagonistic force or air pressure diiierence is chosen in such manner as to obtain a phase difference between the beginning of the starting periods of the two auto-generators equal to the value above indicated.

Of course, I may also differentiate both the rate of flow and the mass of the air that is to be set into movement for opening the starting valve of each of the machines to be started.

.In the preceding description, I have more especially referred to groups of two free piston machines to be started with a phase difference equal toone half ofthe period of oscillation of the movable -unit off these machines or an odd multiple of this value; eourse-myinvention is not-limited tothe case where the number-10f free piston machines to started withapredetermined ph'ase differen fr macommonco'ntrolmemberis equal totwo.

' Furthermore; should be noted that free pis-- tori machines," "for practical purposes; are, gen erally provided with opposed pistons and not s'imple' pist'ons'such as shownby Fig.1 1, for the k o n mp i In aj'general manner, while I have,finthe abovedescription, disclosed-what I deem to b rm wg fl a d ifi sm ed m t o my; 1 should befvvell understood that; I do en ng l ,7 not-wish to' be'limitedj "thereto as there might be changes ade in the arrangementi'disposition and form t rthelp"art "without departing mini theprincipl of the present invention as compr bended within ,s'jcope 'ofthe accompany;-

ing'clairns f v w v ef'I ii i p 1'. Inj'combination twith' a "plant including at least two free pistonmachines; a starting control device which comprises; in combination, a compressed'air' reservoir forfstartingoneof said machines; a starting valve for placing, saidimachine in communication vw '1 s'aifd rese'rvoir, a cylinder op'ening'atbne en into said" reservoir, a piston movable in sa 2 cylinder forming. a movable partition betweensaid'reservoir and the chamber of said cylinder"located.on the other side of said piston; from said reservoir, said piston" being operativel'y "connected with said starting" valve to open 'itfwh'enxthe pressure in .said cylinder" chamber drops! to substantially atmospheric pressure; a compressed air. reservoir for startingthe: oth'erfmachine, a starting .valve for placing said secofid'nrientioned machine in' communication with said" last: mentioned reservoir, a cylinder opening at one end into said second mentioned reservoir, 'a piston movable in said last mentioned cylinder forming a movable partition between said last mentioned reservoir and the chamber ofsaid last mentioned cylinder located on the other side of said last mentioned piston from said last mentioned reservoir, said last mentioned piston being operatively connected with said last mentioned starting valve to open it when the pressure in the said last mentioned cylinder chamber drops to substantially atmospheric pressure, means for filling each of said cylinders with gas under pressure, a common cylinder including a cylindrical wall and two end walls, a piston slidable in said third mentioned cylinder, this last mentioned cylindrical wall being provided with two ports located both on the same side of this last mentioned piston, these two ports being of diiferent sizes and communicating with said two cylinder chambers respectively, a valve rigidly connected with the last mentioned piston'mounted in the end wall of said third mentioned cylinder located on the same side ofsaid last mentioned piston as said two ports, whereby said two ports are connected with the atmosphere when this last mentioned valve is open, a conduit opening into the chamber of said. third mentioned cylinder located on the other side of saidlast mentioned piston from said two ports, a source of gas under pressure, and control valve means for connecting said last mentioned conduit either with said source or with the atmosphere.

2. In combination with a plant including at trol device which comprises in combination, a compressed air reservoirforstarting one ,of said machines,; astarting valve for placing said machine in communication with said reservoir, a cylinder opening at one end into said reservoir, a piston movable in said cylinder forming a movable partition betwee n said reservoir and the chamber of said cylinder, located on the other side of said piston from said reservoir, said piston being operatively connected with said starting valve to open it when the pressure in said cylinder chamber drops to substantially atmospheric pressure-a compressed air reservoir for starting the other machine, a starting valve for placingv said second mentioned machineyincommunication withjsaid last mentioned reservoir, a cylinder openin ,at one, end'into said second mentioned reservoir, a piston movable in saidlast mentioned cylinder forming a movable partition between said last mentioned reservior and the chamber of said last mentioned cylinder located on theother side of said last mentioned piston from said last mentioned reservoir, said last mentioned piston being operatively connected with said last mentioned starting valve to open it when the pressure 'in-the said last mentioned cylinder chamber drops to substantially atmospheric pressure, a common cylinder including a cylindrical wall and two end walls, a piston slidable in said third mentioned cylinder, this last mentioned cylindrical wall being provided with two ports located bothon the same side of this last mentioned piston, these two ports being of different sizes and communicating with said two cylinder chambers respectively, a valve rigidly connected with the last' mentioned piston mounted in the end wall .of said third mentioned cylinder located on the same side of said last mentioned piston as said two ports whereby said two ports are connected with the atmosphere when this last mentioned valve is open, a conduit openinginto the chamber of said third mentioned cylinder located on the other side of said last mentioned piston from said two ports, meansiorming passages between said conduit and each of the two first mentioned cylinder chambers respectively, check valves in said passages respectively opening toward said two first mentioned cylinder chambers, a source of gas under pressure, and control valve means for connecting said last mentioned conduit either with said source or with the atmosphere. v i

3. A starting control device according to claim 2 further including means forming passages between said conduit and each of said reservoirs, and check'valves insaid last mentioned passages respectively opening toward said reservoirs.

ROBERT HUBER.

REFERENCES CITED The following references are of record in the file of this patent:

' V UNITED :STATES PATENTS Number 531,465 Great Britain Jan.'6, 1941 

